Mother enters mental illness plea over son's murder

The Supreme Court has been told a woman was discharged from a psychiatric hospital a month before she allegedly killed her son.

Shan Shan Xu is charged with murdering her four-year-old son in March of 2003. She has pleaded not guilty to the charge by reason of mental illness.

The start of the trial, without a jury, in the Supreme Court has been told the four-year-old drowned after he was taken into the Parramatta River at Meadowbank by his mother.

The Crown prosecutor has told the court Ms Xu was admitted to hospital with psychotic depression in February of 2003, but discharged shortly afterwards when she was thought to be at low risk of harming herself.

Justice David Kirby has been told he will hear evidence from both the prosecution and defence that Ms Xu was suffering from a severe depressive illness when she killed her son a month later.